Control linkage for hydraulic draft regulation of vehicle propelled implements



Sept- 23, 1952 w. F. sTREHLow x-:T AL 2,611,307

CONTROL LINKAGE FOR HYDRAULIC DRAFT REGULATION OF VEHICLE PROPELLED IMPLEMENTS Sept 23, 1952' W. F. sTREHLow ETAL 2,611,307

CONTROL LINKAGE FOR HYDRAULIC DRAFT' REGULATION OF VEHICLE PROPELLED IMPLEMENTS Filed Aug. 23, 1948 2 SHEETS-SHEET 2 Patented Sept. 23, 1952 REGULATION F VEHICLE Ill/[PLEMENTS` PROPELLED Walter F. Strehlow, Wauwatosa, and Igor Kamlukin, Milwaukee, Wis., assignors to Allis- Chalmers Manufacturing Company, Milwaukee, Wis., a corporation of Delaware Application August 23, 1948, Serial No. 45,684

Claims. (Cl. 597-50) This invention relates to mechanical movements generally and is more specifically directed to a connecting linkage having particular utility, although not limited in its application, with respect to a hydraulic control system affording automatic draft regulation of a vehicle propelled implement; certain features herein shown and described but not claimed are disclosed and claimed in our copending application Ser. No. 26,516, filed May 12, 1948, Hydraulic Apparatus with Variable Discharge of Pressure Maintaining Fluid.

It is an object of this invention to provide in a hydraulic control system a connecting linkage constructed and arranged to transmit movement from a forcerresponsive part to a pump regulating valve in an improved manner such that as the force on said part increases the resulting movement of the valve decreases.

Another object of this invention is to provide a linkage Whichtransmits movement of a force responsible movable part to a hydraulic pump control valve and which linkage includes an element arranged in a novel manner so as Vto move in spaced relation to said valve through one predetermined range and also move with said rvalve through another predetermined range.

It is a further object of this invention to provide an apparatus for controllably shifting the position of a device through the operation of means including a pump, valve and a force responsive part wherein the part and valve are connected through an improved linkage affording movement of said valve in response to movement oi said part-.and including a lockout means positionable to render said linkage ineffective to transmit movement of said part to said valve.

A still further object of the present invention is to provide an apparatus for controllably shifting the position of a device through the operation of means including a pump, valve, pump unloading means, manual control lever and a force responsive part wherein the part, control lever, valve and unloading means are connected through an improved linkage including the lockout means mentioned hereinbefore, and wherein said linkage affords movement of said valve in response to either actuation of the control lever or the'pump unloading means when the lockout means is ernployed to prevent response to draft.

An additional object of this invention is to provide a connecting linkage for use in a hydraulic control system which is simple, compact and relatively inexpensive to manufacture and service and/or which is inherently capable of accomplishing one or more of the above stated objects.

' y The construction and operation of apparatus capable of accomplishing the above stated objects will become readily apparent as the disclosure progresses and particularlypoints out the various advantages and features considered of special importance. And accordingly, the present invention may be considered as comprising the various features of construction, combinations and subcombinations of elements or parts as is hereinafter more fully set forth in the detailed description and appended claims, reference being had to the accompanying drawings in which:

Fig. 1 is a partial view of a tractor having apparatus embodying the invention mounted thereon with the near driving wheel removed and parts broken away to more clearly show the apparatus; Fig. 2 is an enlarged plan view taken along line II-II in Fig. 1;

Fig. 3 is an enlarged sectional plan view of the control linkage taken along line III--III in Fig. 1; Fig. 4 is a view taken along line IV--IV in Fig. 3; Fig. 5 is a schematic illustration of the control system with-some parts shown in section to afford a better understanding of its operation;

Fig. 6 is a sectional view showing the relation of the main valve to the passages controlled thereby when the valve is in its implement lowering position;

Fig. 7 is a View similar to Fig. 6 showing the valve positioned to allow all pumps to discharge liquid to the ram;

Fig. 8 is a partial view of the main valve and control passages showing the valve positioned to hold the'imp'lement in raised or partially raised position with all pumps discharging liquid to the return passage means; and

Fig. 9 is a View similar to Fig. 8 showing the valve in its full lowering position with the valve engaging means having moved away from the end of the valve.

Referring to Fig. 1, it will be seen that the apparatus chosen to illustrate the present' invention comprises generally a tractor l having rear driving wheels 2 and a frame 3, and an implement comprising a moldboard plow 5 attached to the tractor in rearwardly extending relation to rear driving wheels 2.

vMounted forward of and below the rear axle housing 6 is a drawbar support l adapted for connecting the implement tothe tractor in draft transmitting relation therewith. Drawbar sup'- port 'l comprises a pair of laterally spaced plate members 8 xed in depending relation to the underside of the tractor, as by welding, a lever I integrally formed with a bearing means II adapted for positioning same between plate members 8, and a pin I2 extending through aligned openings in the lower portions of plate members 8 and through bearing portion II of lever I0, thereby supporting the lever for swinging movement about pin I2. The lower portion of lever I0 is provided with a bearing means I3 supporting a pivot pin I5 which in turn is connected to and supports the forward end of a drawbar structure I6. The upper portion of lever III, hereinafter called the draft regulating lever, is acted on by biasing means comprising a spring seat I1 rigidly fixed between upper forward portions of plate members 8 in transverse relation therewith, a compression spring I8 positioned on the seat, and a plate member fixed to the opposite end of the spring for engagement with forwardly projecting portions 2I of the regulating lever. Ihus it will be seen that draft force applied to the lower end of regulating lever I0 through drawbar structure I6 is opposed by the compressive force of spring I8 acting on the upper end of this lever.

Referring also to Fig. 2, it may be noted that drawbar structure I5 comprises a bar member 22, a yoke 23 and pin 25 connecting the forward end of tne drawbar with pivot pin I5 carried by draft regulating lever II) for vertical and hcrizontal swinging movement of the drawbar relative thereto. and an opening (not shown) in the rear portion of bar member 22 for receiving a pin 26 adapted to connect with an implement. In addition, there is provided a structure for guiding the swinging movement of the drawbaig.

this structure including pairs of similar parts of which only one such part is shown in Fig. l as it will be obvious that identical parts occupy a similar position on the opposite side of the tractor. As indicated, the guiding structure comprises a pair of vertical plate members 21 fixed to the under portion of rear axle housing 6 in depending laterally spaced and generally parallel relation with respect to each other, a pair of similar strap members 28 having their upper ends pivotally mounted on coaxially aligned pins 30 carried by plate members 21, a transverse guide bar 3I positioned between and carried by the lower end portions of strap members 28 for rotation about a transverse axis, and a guide strap 32 fixed to the rear half of bar 22, as by bolts 33, in overlying vertically spaced parallel relation therewith. Guide bar 3| and guide strap 32 coact to afford guided swinging movement of drawbar I5 in both a horizontal and vertical direction. Each strap member 28 is provided with an opening 35 adapted for alignment with a selected one of a series of openings 36 arcuately spaced along the rear portion of the adjacent plate member 21 for placing a pin 31 therethrough to adjustably limit the lowering movement of the drawbar.

Implement 5 comprises a conventional moldboard plow 33 fixed to a forwardly extending beam 46 having a downwardly arched forward portion 4I. A bar member 42 curved similarly to portion 4I of plow beam 45 is disposed in laterally spaced relation thereto, being rigidly fixed to beam portion 4I by means of plate 43 and spacing member 45. Plate 43 and member 45 interconnect bar 42 with arched portion 4I in a suitable manner such as by welding. In addition, a pair of vertically spaced strap members 46 are fixed between the rear portion of bar 42 and adjacent beam portion 4I and have aligned openings (not shown) therethrough for alignment with a similar opening (also not shown) in guide strap 32. The forward ends of beam portion 4I and bar 42 have coaxially aligned openings therethrough for receiving a pin 41. To attach implement 5 to drawbar structure I6 the forward portion of plow beam 40 is placed so that plate member 43 underlies bar 22 with the openings in straps 46 aligned with the opening in the rear portion of guide strap 32 and the pin 26 inserted therethrough. Pin 41 is then placed through the aligned openings in the forward ends of bar 42 and beam portion 4I and rests against guide strap 32 thereby preventing vertical swinging movement of the plow relative to drawbar structure I6. The above described method of attaching implement 5 to drawbar structure I5 affords a rigid connection therebetween making the combined structure movable as a unit relative to pivot pins I5 and 25.

For lifting and lowering the implement, that is vertically swinging implement 5 and drawbar IE as a unit about the support for the latter afforded by pivot pin I5, there is provided a power lift means comprising generally a hydraulic pump 48 operatively connected to the tractor power source in any suitable manner such as the cam and follower arrangement shown schematically in Fig. 5, a ram 5I] receiving fluid from the pump through a conduit 5I, and a ram actuated lift mechanism operatively interconnecting ram 5D and implement 5. The lif-t mechanism includes a vertically disposed plate member 52 xed to and extending rearwardly from rear axle housing B, and a bellcrank lever pivotally attached to plate member 52 by pin 53, or other suitable means. This bellcrank lever has one arm 55 pivotally connected with the rearwardly extending piston rod 56 of ram 50, and has its other arm 51 extending rearwardly and pivotally supportedly connected with the upper end of a lift rod 58 which has its lower end pivotally connected with the underlying plow beam 46. f

Looking at Fig. l, it will be seen that draft regulating lever I0, which part is movable in response to a draft load imposed on drawbar I6 as previously explained, is connected with the hydraulic pump unit 48 through a link 60 having a pivotal connection with the upper end portion of lever I0 and a lost motion connection (pin and slot) with an arm 6I extending from the pump control housing 62. Thus it is apparent that drawbar I6 is operatively connected with hydraulic pump 48 and it will be seen further along in the disclosure how this connection controls the action of the pump.

Referring now to Fig. 5, which is a schematic illustration of pump 48 and of the controls therefor it will be seen that this apparatus comprises generally a source of liquid 63, a plurality of pumps (four in `this case) each having communication with the source 63, a control valve 66, and a pressure relief means 61. The pumps, which are a plunger type, have cam followers 68 for engagement with cam portions 10 of a power driven shaft 1I, and each pump has a discharge passage 12 communicating with control valve chamber 13. In addition, there is provided a separate chamber 14 which serves as a discharge manifold and communicates with control valve chamber 13 through check valve controlled passages 16 conforming in number to pump discharge passages 12. And in this connection it should be noted that passages 12 communicate With Valve Chamber 'I3 in diametrically opposed relation to passages 10. Discharge manifold 14 communicates at its right hand end with a check valve controlled outlet passage 11 through which working fluid is carried to a pressure actuated device such as ram 50.

Looking again at control valve chamber 13 it will be seen that a cylindrical liner comprising axially separable sections 80 to 84 is disposed in the cylindrical control valve chamber with the end sections 80 and 84 being held in place by cover plates 86 and 81, respectively. Cylindrical sections 80 to 84 are provided with circumferential external grooves 88 placing pump discharge passages 12 in communication with the check valve controlled passages 16. In addition each section is provided with transverse bores 90 placing the interior thereof in communication with the diametrically opposed pairs of passages 12 and 16. Furthermore, the endV abutting portions of cylindrical sections 80 to 84 have parts thereof cut away and shaped to afford circumferential external grooves 8|, rectangular in cross section, each of which communicates with the interior of the chamber formed by these sections through diametrically opposed transverse passages 82. The rectangular external passages formed between end portions of cylindrical liner sections 80 to 84 communicate with exhaust passages 93 which in turn communicate with a main return passage leading to the iluid source or reservoir 63. In addition, the innermost cylindrical section 84 is provided with two additional circumferential external grooves 96 and 81, groove 81 communicating with ram outlet passage 88 and with a transverse bore |00 placing diametrically opposed portions of groove 31 in communication with the interior of section 84, whereas groove 96 communicates with a passage |0| which in turn communicates with the right hand end of main fluid return passage 95. Groove 86 also communicates with the interior of liner section 84 through diametrically opposed transverse bores |02.

A cylindrical control valve 66 is positioned in the generally cylindrical chamberl formed by the end abutting liner sections 80 to 84 and preferably this valve is formed by a series of separable cylindrical elements |04 to |01, inclusive, disposed in end abutting relation, the end abutting portions of these cylindrical valve elements being reduced to form annular spaces betweenv same andthe surrounding internal surfaces of the liner sections. In this connection it should benoted that the right hand or yinnermost valve element |01 comprisesan intermediate reduced portion |08 uniting enlarged cylindrical portions ||0 and which in turn terminate in reduced oppositely projecting end portions, the inner one of Which abuts the reduced portion of adjacent element |06 and the other of which projects through a coaxial opening ||2 in coverplateril (see Fig. 3). The valve elements are held in end abutting relation for movement as a unit by means of a compressionv spring ||3 seated on' valveelement |04 in surrounding relation 'to the reduced outer end portion thereof with vits opposite end rabutting the inner surface of cover plate 86. Movement of the valve element to the left as viewed in 5 may be adjustably limited through the medium of an inwardly projecting part ||5 carried by .cover member 86, this part having an internally threaded bore I6 extending therethrough in which is adjustably mounted a screw'threaded element |1 having a reduced end portion I8 disposed in coaxial abutting relation with respect to a similar projection on the adjacent valve 6-A element |04. The outer exposed end of element I l5 is provided with a knurled knob |20 to facilitate adjustment thereof.

Looking now atthe top portion of Fig. 5'it will be noted that the pump unit includes a second cylindrically shaped chamber 61 including parts operative as a pressure relief and unloading means. This unloading chamber communicates with the left hand endof discharge manifold space 14 by means of a passage |2| and an intermediate portion of this unloading chamber also communicates with a fluid return passage |22 having communication with reservoir 63. The left end portion- |23 of unloading chamber 61 is somewhat enlarged'to provide an internal shoulder |25 against which is positioned a diskrtype spring seat |26 having'an-opening |21 therethrough. The opposite or left hand end of chamber portion |23 is closed by a cylindrical plug element 28 having an inner end portion |30 of reduced diameter projecting axially toward spring seat |26 in spaced relation with respect to the surrounding wallof chamber 31. The outer or left hand end of plug element |28 abuts and is kept in place by cover plate 86. The left hand end of plug member |28 is provided with a circumferential external groove |3| communicating with passage I2| leading thereto from manifold 14. A transverse bore |32 connects diametrically opposed portions of groove |3| with a central bore |33 which extends inward from transverse bore |32 and coaxially through the reduced portion |30 of plug member |28. Central bore |33 is somewhat enlarged from a point adjacent transverseV bore 32 to the discharge side thereof to provide a seat for ball valve |35 and to receive a cylindrical valve element |38. A `cylindrical springV seat element |31 slidably surrounds the reduced end portion |30 of plug member |28 and is provided at its open end with' a peripheral flange |38 slidably engaging the internal surface of unloading chamber portion |23, this flange also affording a seat for a compression spring |40.dis posed between same and disk seat |26. The inner end of element |31 is provided with an internal recess forming a cylindrical seat |4| receiving the inner end of cylindrical valve element |36 which, through the action of spring |40, acts to hold this valve element and ball valve |35 in a passage closing position, that is, with the ball valve firmly engaged with its seat thereby preventing a flow of fluid therepast from manifold 14. And when thus positioned, the flanged end portion |38 of spring seat element |31 is spaced from the oppositely facing shoulder presented by plug member 28. The reduced portion |30 ofv plug member |28 is provided with a transverse bore |42 therethrough and is further reduced from its junction with the main portion of the plug member |28 inward t0 a point beyond transverse bore |42 so as to provide anannular relief passage |43 which communicates with the spring housing portion of chamber 61 through one or more axial slots |45 in the peripheral edge portion of flange |38. Cylindrical valve element |36 is also provided with an axial bore |46 extending from the ball valve end thereof approximately to its midpoint where it communicates with a circumferential groove |41 adapted to place the space between the endvof valve element |36 and the seat for ball valve |35 in communication with the transverse bore |42 inplug member portion |30, thus providing a relief passage means for the space surrounding ball valve |35 when seated. Also, the inner end portion of cylindrical spring seat element |31 is provided with transverse bore I48therethrough for relief of any liquid accumulating between same and the inner end of plug member reduced portion |30.

The right hand end of unloading chamber 51 mounts a cylindrical spring seat |50 and is closed by cover plate B1. A pressure responsive piston is mounted in unloading chamber |51 in downstream relation with respect to spring seat disc and is detachably connected (not shown) with a movement transmitting rod |52 which extends coaxially through cylindrical spring seat and through an aligned opening |53 (see Fig. 4) in cover plate 81. Referring also to Fig. 3 it will be seen that the outer or exposed end of control rod |52 is iixedly connected with and carries a stub shaft which projects at a right angle therefrom in the direction of valve chamber 13 and in generally parallel relation to cover plate 81. A compression spring |56 (Fig. 5) is interposed between seat |50 and the opposed end of piston |5| in surrounding relation to piston rod |52, this spring acting to move the piston toward the left in closed relation with respect to fluid return passage |22. It will be noted that the right hand end of unloading chamber E1 is provided with another iiuid return passage |51 having communication with reservoir 63 and functioning to return any liquid which may become trapped Ibetween piston |5| and cylindrical spring seat As seen in Figs. 3 and 4, it will be apparent that shaft |55 carried by control rod |52 operan tively mounts a sleeve |58 having an enlarged portion positioned in opposed engaged relation with respect to the reduced end portion of the innermost valve element |91 which extends through cover plate 81. A motion transmitting means comprising a plurality of associated elements positioned within housing 52 operatively connects shaft. |55 with shaft regulating link 60. More particularly, a first element, lever |6l, has its upper end portion lixedly secured to sleeve |53 for rotating movement therewith relative to shaft |55, and a second element, link |63, has one end pivotally connected to an intermediate portion of lever |6|. The other end of link |63 is pivotally connected with an arm fixed to an inner end portion of a shaft |66 rotatably supported in a bearing structure |81 carried by control linkage housing 52. element, cam lever |35, has a lost motion pivotal connection at one end (pin |81 and slot |55) with the lower end portion of lever |5|, that is, the end remote from shaft |55. The other end of cam lever |85 is iixed to a shaft |83 rotatably mounted in a bearing means (not shown) carried by housing 62. A fourth element, arm 58|, fixed at one end to a shaft |16 rotatably supported by the linkage housing has a pin |62 at its free end adapted and positioned for engagement with a curved edge |85 of cam lever |55. All of these elements are disposed within housing 62 which is detachably secured in abutting sealed relation against cover plate 81 by means of cap screws |68 or the like. l

The outer end of shaft |56 has an arm |18 fixed thereto which in turn is connected through a link |1| with a suitable manually actuable control lever |12 (Fig. l) carried by the tractor steering column |13 and associated with a quadrant |15 (Fig. 5). The portion of shaft |15 projecting outside of housing 62 has a triangular arm 6| fixed thereto at one apex with another apex thereof connected with draft regulating link 66 by means of a pin |18 which slidably engages A third a slot in the adjacent end of link 60. And in this connection it should be noted that the third apex of arm 6| carries a lockout screw |90 engageable with an internally threaded bore |9| in the lower portion of housing 52. For readily turning screw |90 a knurled knob |92 is provided, and a spring |93 (Fig. 3) is positioned between knob |92 and arm 6| for urging screw |90 outwardly and thus preventing displacement of same due to vibration of the pump and control unit. this being particularly useful when said unit is mounted on a tractor.

From the foregoing description it should be apparent that manual control lever |12 may be moved so as to shift the fulcrum for lever |6I, that is the fulcrum |52 afforded by the connection of link |63 to an intermediate portion of lever |6|, and thereby move the tcp of lever |6| relative to cover plate 81. Also, movement of draft regulating link E5 transmitted through arms 5| and |6| and lever |85 causes a swinging movement of lever |6| about the fulcrum point |62. More speciiically, spring |55 in unloading chamber 61 is relatively strong as compared with the spring H3 acting on control valve 55 and consequently control rod |52, stub shaft |55 and valve 65 tend to assume the positions shown in Figs. 3 and 4. Therefore, the above mentioned position (shown also in Fig. 7) of valve 5S, control rod |52 (and consequently piston |5| may be changed either (l) by moving manual control lever |12 to effect a shifting of fulcrum |62 in a direction away from cover plate 81 and thus pivot lever |6| about pin |81, or (2) by a movement of draft regulating link 60 away from pump control housing 62 causing pin |82 to engage cam lever |85 and thus swing lever |6| in a clockwise direction about its fulcrum |52. Either of these actions move rod |52 and piston l5! toward the right, as viewed in Fig. 5, which in turn compresses spring |56. As a result of such movement spring I3 urges control valve 55 toward the right and acts to maintain the reduced right hand end of this valve in engagement with roller |60. Movement of the valve in the vdirection just described, that is, toward the right is limited by engagement of the enlarged portion I of valve element |01 with cover plate 81.

When operating with the parts positioned to obtain maximum lifting effect, that is, in their full lift position wherein hand control lever |12 is in position A (Fig. 5), wherein the control linkage is positioned as shown in Figs. 3 and 4, and valve 65 is positioned as shown in Fig. '7, it will be noted that the enlarged cylindrical poi'- tions of the valve elements |04 to |01, inclusive, close transverse bores and that, therefore, the pumps are severally connected with manifold bore 14 through passages 12, external grooves |38, and through check valve controlled passages l5. The liquid entering manifold space 14, assuming al1 liquid has been drained from the ram 50, flows therefrom through check valve controlled passage 11 and quickly attains a pressure sufc1ent to rapidly effect a weight lifting power stroke or expansion of the ram unit. When this occurs the pressure of the liquid in the manifold space 14 continues to increase until the pressure attamed is suiiicient to unseat pressure relief ball valve |35 whereupon the check valve assembly comprising ball valve |35 and cylindrical valve element |36 moves toward the right compressing spring |40 until valve element |36 opens transverse pressure relief bore |42. This permits pressure iiuid to flow through bore |52 and into annular space |43, then through the axial passages |45 in the periphery of ange portion |38 of spring seat element |31, then into the spring housing chamber from which it flows through the opening |21 in disc spring seat |26 and into the space between this seat and the head of piston |5|. This pressure uid then acts on piston |5| and moves same toward the right thereby opening relief passage |22 which is in communication with the liquid source 63. This movement of piston |5| results in a movement of control rod |52 towardrthe right suiicient to bring the lower end of lever |6'| into engagement with the side of cover plate 81 which engagement limits the movement of the piston |5| and control rod |52 in this direction. As a result spring ||3 causes control valve 66 to move toward the right in following engaged relation to enlarged part |60 of sleeve |58 and to the position indicated in Fig. 5. In this, the pump unloading position, the enlarged bore controlling portions of'valve elements |04 to |06, inclusive, place transverse bores 90 in the associated liners in communication with the main return passage 95. However, it should be noted that the enlarged portions and of valve element |01 remain in closed relation with respect to associated transverse bores 90 and |00, respectively, and therefore the associated pump 65 continues to deliver fluid through circumferential groove 08 and intov manifold space 14 through the associated check valve controlled passage 16.

In the absence of excessive leakage, more particularly leakage through the flexible hose and the connections between such hose and the ram cylinder andpump housing, main control valve 66 will remain in its unloading position until either fulcrum |62 of lever |6| is shifted by actuation of manual control lever |12, or until a change in draft force moves regulating link 60 to cause cam lever |85 to swing lever |6| about its fulcrum |62, and with control valve 66 in its unloading position the hydraulic ram unit 50 will remain in its extended weight lifting position, but if vfor any reason the pressure in manifold space 14 should decrease below that necessary to hold ball valve |35 and cylindrical relief valve |36 in their passage opening position these valves will close the relief passage means |2| and as the liquid drains from the space ahead of piston |5I, spring |56 will move piston |5| and control rod |52 to the left thus repositioning the main control valve 66 to connect all pumps to manifold 14, this initial position of main control valve 66 being determined, as previously indicated, by the position of manual control lever |12.

However, if with the control valve 66 in either its full lift or unloading position, previously described, it becomes desirable to lower the weight or implement 5 all that has to be done is to move manual control lever |12 to a lowering position, that is, a position in the range B-.D on the quadrant |15 shown in Fig. V5. Movement in this direction is effective to shift fulcrum |62 for lever |6| away from cover plate 81 a distance sufficient to permit spring I3 to move main control valve' 66 to the right until the discharge sides of all pumps and the ram relief passage means 98 and |00 are in communication with return passages 93 and |0I, respectively, which in turn are in communication with the return passage means 95. Under these conditions liquid rapidly drains from the ram circuit, ram piston" |95 moving to its retracted position through gravity action of the weight or other means-actuated thereby. In other words, if the vWeight were to be considered as representing an agricultural implement or other load, a movement of valve 66 to its lowering position shown in Figs. 6 and 9 rapidly drops the implement to the ground. If, however, it is desired to gradually lower the weight or implement onto the ground, this can be readily accomplished simply by moving valve 66 so as to just barely open the passage means |00 placing the ram relief passage 98 in communication with the return passage means |0| and-95. And if, in this connection, it should be desired to placeall pumps in communication with the return passage means 95 through passages 93 and yet retain the ram in its extended position, this can be readily accomplished by manually shifting` fulcrum |62 of Ylever |6| so as to position main control valve 66 as indicated in Fig. 8. When thus positioned it will be seen that the enlargedportion of the cylindrical control valve section |01 closes the transverse bore |00 to prevent placing the ram relief passage 98 in communication with the return passage means |0|.

It should also be obvious that in addition to the various positions of the main control valve hereinbefore described, valve 66 may also be positioned by a manual shifting of the fulcrum |62 for lever |6| so as to, if desired, effect a rarn expanding action by connecting the discharge sides of one or more pumps withthe checkvalve controlled passages 16 connecting samel with manifold space 14. And while it is normally intended that the enlarged cylindrical portions of main control valve 66 will be positioned so as to either open or close the radially extendingV transverse bores or passages 90 and |00, placing the circumferential external grooves 88 and 91 in communication with the interior of the valve chamber formed by liner sections and 84, inclusive, it should be obvious that theV valve elements may be positioned so as to only partially open one or more of the transverse passages 90 and 91. Furthermore, it should be apparent that while the particular arrangement of the passages and valve elements herein shown for purposes of illustration constitutes a preferred embodiment of the present invention, other arrangements can be readily made as Vdesired simply by changing the axial spacing of the control passages 90, 92, |00 and |02, circumferential grooves 88, 9|, 96 and 91 and/or the axial length ofthe enlarged passage controlling portions' of valve elements |04 to |01, inclusive.

Referring generally now to Figs. 1 and 5, the operation of apparatus embodying the present invention will be described with specific reference to other gures being made as the description progresses. Assuming that manual control lever |12 has been movedto position A on quadrant |15 (this'shifts the fulcrum |62 of lever |6| to its limiting position nearest cover plate' 81) and that the attached plow 5 is in its transport or fully raised position to begin with, the action of the apparatus will be described as the plow is lowered to the ground andassumes a soil working position. When the implement has been fully raised valve 69 will have moved to its unloaded position (Fig. 5) and the lower end of lever |6| will have moved from its position shown in Fig. ll to a position abutting cover plate 81. To Vlower the implement the operator moves the manual control lever |12 from position A to a lowered position (somewhere linrange B-D), for example, the position designated D inA Fig. 5, wherein control valve 66 assumes the position shown in 1.1 Fig. 9 with all pumps delivering through transverse passages 040 and 9,2, grooves 9| and passages 93 back to the source 63 and the ram clischarge passage 8 has commuication with ram relief passage |0| through'control valve chamber 13. Movement of control lever |12 to this full lower position, i. e. to position D on Fig. 5, pivots lever |6| about pin |81 in a clockwise direction thereby moving stub shaft |55 and sleeve portion |60 to the right and away from control valve 66 which'is also moved by the action of spring |3 to its farthermost position to the right as shown in Fig. 9. The weight of the implement then forces ram piston |95 back to its retracted position (not shown) and the implement rests on the soil.

Having determined through pervicus experience the amount of draft which gives a desired depth of soil penetration forV the plow in a particular field, the operator next Vsets control lever |12 to that predetermined position on quadrant |15; that is, to a position within the draft regulating range designated B-D. This in effect shifts fulcrum |62 back to the left to a point,

intermediate its limiting positions thereby causing sleeve portion |60 to approach cover plate 81 and to approach or contact the adjacent end of valve 66, lever |6| being once more pivoted counterclockwise about pin' |81. As previously indicated, this selectedv position will be in the lowering range of the control valve travel with no pumps delivering to manifold '14. When the tractor moves forward the point of theplow entersA the ground and a tensive draft force is transmitted through drawbar structure I6 to the lower portion of draft regulating lever |0. This application of force increases as the plow goes deeper into the ground and, as a result, lever |0 pivots against the resistance offered by spring I8 thereby moving draft regulating link 60 forward so that the left end of slot |86 therein tends to move away from pin |18 on arm 6|. Actually, however, the spring |56 surrounding control rod |52 causes pin |18 to follow the left end of slot |80 in its movement.v That is, spring |56 which always tends to move the upper end of lever |6| in to abutting relation with cover plate 01 is dominated by the action of spring |8 which under no load holds slot |80 in a fixed position which by virtue of the coaction of the pin |18, arm |8| and lever |85 prevents clockwise movement of lever |6|. However, when force is applied to drawbar I6 compressing spring |,8y draft regulating link 60 moves forward (to the left as viewed in Figs. 1, 4 and 5) thereby allowing pin |18 to move upward to the left which permits arm 6|, shaft |16 and arm |8| to move counterclockwise so that downward movement of pin |32 permits counterclockwise movement of lever |85 and consequently lever |6|, the latter turning about its adjustable fulcrum or pin |62. This movement is accordingly limited by the enlarged sleeve portion '|6l0jstriking, cover plate 81 or by cessation of movement of draft regulating link 60 due to its having reached the normal position for any given load on the drawbar.

The counterclockwise movement of lever |6| operates to bring the enlarged sleeve portion |60 on shaft |55 into engagement with the adjacent end of valve' 66 thereby moving same to the left and into an implement raising position, thel eX- tent of such movement depending on the position of fulcrum |62 as determined by the selected position of manual lever |12. As the implement lifts due to one or more pumps delivering liquid to ram unit 50, the draft force transmitted to acuso? lever I0 decreases and as a result spring l0 will move link rearwardly thereby turning shaft |16 and the arms 6| and |8| thereon in a clockwise direction which in turn effects a similar movement of lever 6| about its fulcrum |62. And it should now be obvious that this resulting movement of lever ISI permits spring ||3 to move valve 66 to an implement lowering position conforming with the decrease in draft force and the position of hand lever |12.

In connection with the above described movements of the linkage in control housing 62, it will be noted that the edge portion |66 of lever |85 which is engaged by Din |82 is in effect a cam and this construction affords a coaction of parts which is very advantageous in a draft regulating system. As shown in Fig. 3, the parts in housing 62 are positioned with control valve 6,6 in full lift (lever |12 at point A in Fig. 5) and no load is being transmitted through draft regulating link 60. As load is applied to drawbar |6 and regulating link 60 moves to the left, lever 8 is permitted to move in a counterclockwise direction as previously described. The curved edge portion |86 of cam lever |85 is so designed that this counterclockwise movement of lever |8| results in an increasingly greater movement of pivot |61 (between lever |6| and cam lever |35) to the right for the same amount of movement of draft regulating link 60;. Practically speaking this means that for any given setting of manualy control lever |12 the variation in force at the drawbar necessary to` effect a regulating movement of control valve 66 will be a predetermined percent of the draft at that setting. Assuming cam surface |86 as shown is designed for a regulation of draft within ten percent, then for a setting of hand lever |12 for say a draft of 700 lbs. it will take an increase or. de.- crease in draft of lbs. before any regulating movement of main control valve 66 will be effected, whereas fora, draft settingof 250,0 lbs. on quadrant |15 itl will take a variation, of 250 lbs. in draft force before movement of control valve 66 is effected. The result of this, variable response afforded by the present invention may be more clearly explained by comparing the action of a plow in extreme. soil conditions. When plowing in very lightsoil at a given depth an increase in draft of 70 lbs. maybesufiicientto causethe plow to raise 1/2 inch, whereas in plowing extremely heavy soil at the. same depth itmay take an increase cf 250 lbs. to raise the plow 1/2 inch. It will be obvious, therefore, that although a. control apparatus which is responsive to a definite amount of change, in draft, force could operate satisfactorily for uniform soil conditions and depth, any material change in said conditions would produce an undesirable-hunting effect wherein the hydraulic lift is continually operating and the plow is being raised ,or-lowered too much with respect to the desireddepth.

In traveling throughla fieldwhereinthe type and condition ofthesoil are uniform, lever |6| will operate as hereinbefore described and assume a generally stable position atwhich the draft force balances the lift force produced by the pumps. However, should the type'and/or condition of the soil vary materially and-itisdesirable to plow at the same depthasbefore, a manipulation of manual controlV lever |12 is necessary. For example, if the soilbecomes heavier, hand lever |12 should be shifted Vvtoward point D in the draftregulating range. .thus moving fulcrum |62 further 'toward the rightas'viewed in Figs. 4 and 5, whereas if the-soil become light. lever |12 should be shifted toward point B. In

ever hand lever |12 is positioned in the range A-B one or more of the pumps are operating to deliver liquid to ram unit D and when this lever is positioned at point B, or immediately adjacent thereto within a very small range, all pumps are delivering to return passages 93 and ram relief passage |08 is closed (this being the hold position shown in Fig. 8). Further movement of lever |12 within range B-C opens ram relief passage |08 permitting fluid in the ram 50 to return to source 63.

Therefore, it should be obvious that the rate at which an implement can be raised or lowered depends upon the position selected for lever |12 within the ranges A-B and B-C, respectively,

that when the lever is within range A-B and adi jacent point A the rate of lifting is a maximum, and that when the lever is within range B-C and adjacent the holdf position described abovethe rate of lowering is a minimum and as lever |12 is moved downwardly away from this fhold position the rate of lowering increases until it reaches a maximum at point C. Movement of hand lever |12 past point C and toward pointD operates to merely move shaft |55 and sleeve portion |60 (attached to the upper end of lever |6I) away from the adjacent end of valve BB and toward the extreme position indicated in Fig. 9, valve 66 being prevented from then following sleeve portion |50 by engagement of its enlarged portion with the innerside of cover plate 81. Consequently, if hand lever |12 be positioned between points C-D, the draft force necessary to bring sleeve portion |68 into operative engagement with the adjacent end of valve 66 is determined and varied in accordance with the selected position of this lever. This'is an important feature in that it affords an effective range of draft regulation without electing a preloading of spring |8 which acts on lever |0 in opposition to the draft induced force thereon. However, if desired, spring I8 may be preloaded thereby increasing the effective range of draft regulation to include all positions of lever |12 between points B and D.

In performing certain operations it is sometimes desirable to have the action of the hydraulic pump controlled entirely by the operator and for this reason there is provided the lockout means described hereinabove (see Figs. 3 and 4) by which arm 6I is Xed to the control linkage housing 62 and movement of draft regulating link 60 is then ineffective to alter the position of control valve 66. With arm 6| thus fixed in position pin |81 becomes a fixed pivot for lever ISI and action of control valve 66 is controlled through operation of hand lever |12.

Another feature of considerable importance is the arrangement of parts so as to afford relative movement between lever 15| and main control valve 66. This relative movement has the effect of preloading spring I8, as mentioned above, without actually so doing and therefore increases the range of effective draft regulation afforded by the system. This feature of construction also affords an additional advantage in that it permits simultaneous movement of valve 66 and lever I8! when needed, particularly in the previously described unloading action of the pump when control rod |52, shaft I 55 and lever IGI move to the right and control valve 66 follows under the compressive force of spring I3.

It is so important, particularly in draft regulation of soil working implements, that the hy draulic lift respond to a lesser variation in draft force when working with light heavy soil, and this is madev possible in the vpresent invention through the particular arrangement Vlof control linkage parts and more specifically is due to the cam lever which coacts `with pin |82 in Ia manner such that as the |draft force increases the resulting movement of control valve decreases.

And it. should be obvious Ythat although the present invention has been described .with particular reference to an automatiodraft regulating apparatus, it is equally adaptablefor Zuse with any device employing a part-whichis to be regulated Iin its movement or conthollably positioned inaccordance with the Iamount of load imposed on or carried by said device. And it'should, therefore, be understood that it is not intended to limit the `invention to the exact constructions, combinations and/or subcombin-ations herein shown and described as various 'modifications withiinthe scope of the -appended claims may oc- -cur to those skilled in the art. t

' It is claimed land desiredto secure by Letters Patent:

l.y In an `automatic ydr-aft control for a ground working implement operated through means including a pump, a hydraulic motor connected -with said implement, a valve movable throughout a predetermined range for control-ling the flow of fluid toand'from said motor, and a movable part responsive to variations in Ian vimplement induced draft force appli-ed thereto, the combination of a `linkage operatively connecting said valve and movable part comprising a first lever movably' vsupported with a first portion thereof disposed for operative engagement with'said valve,ra second lever mounted for swinging movement and having a portion thereof operably connected with la second portion of said first lever remote from said first portion affording relative swinging movement therebetween and rendering said first .lever actuable by said second lever, 1a manual control lever, a link connecting said manual control lever with said rst lever intermediatesaid rst and second portions and affording a fulcrum for said rst lever which is selectively shiftable by actuation of said manualcontrol lever, said first lever constituting a common means operatively connecting said second yand manual levers in motion transmitting relation to said valve and render-ing said manual lever actuable to .position said first porti-on of said iirst lever in a preselected extent of lost motion relation to a limiting position of said valve whereby said second lever must then move an amount proportional to said preselected extent before imparting motion to said valve, and means operatively oonnecting said second lever with said movable part.

2. In an automatic draft control fora ground working implement operated through me-ans including `a pump, a hydraulic motor connected with said implement, a valve movable throughout a predetermined range for ycontrolling the flow of fluid to and from said motor, and a movable part .responsive to variations in an implement induced ,other end portion of said fi-rst lever affording relative swinging movement therebetween and soil than with render-ing same actuable by said second lever, a manual control-v lever, a link connecting said manual control lever with said first lever intermediate said end portions and affording a f-ulc-rum for said first lever which is selectively shiftable by actuation of said manual control lever, biasing means urging said first lever to pivotabout said fulcrum in a predetermined direction, said first lever constituting a common means oper-atively connecting said second and manual levers in motion transmitting relation to said valve and rendering said manual lever actuable to position said first portion of said first lever in a preselected extent of lost motion relation to a limiting position of said valve whereby said second lever must then move an amount proportional to said preselected extent before imparting motion to said valve, and means operatively connecting said second lever with said movable part.

3. In an automatic ldraft control for a ground working implement operated through means inc luding a pump, a hydraulic motor connected with said implement, a valve for controlling the flow of fluid to an-d from said motor, and Ia movable part responsive to variations in an implement induced draft force applied thereto, the combination of a linkage operatively connecting said valve and movable part comprising an elon- Igated first lever Ihaving one end portion pivotally connected with la movable support and positioned thereby for operative engagement with said valve, a manual control lever, a. link connecting'v said manual -control lever with said first lever at, an intermediate portion thereof and affording a fulcrum for said first lever, a second lever mounted for swinging movement and having a portion thereof operably connected with the other end portion of said elongated lever :affording relative swinging movement of said first lever and rendering same actuable by said second lever, a swingable a-rm having its free end portiondisposed for sliding enga-gement with an edge ofA said second lever, said arm being operably connected with said movable part, and biasing means urging said movable support in :a Vpre-determined direction.

4. In an automatic draft control for a ground working implement operated through means including a pump, al discharge passage for said pump, a hydraulic motor connected with said implement .and receiving fluid from said passage, a valve for controlling the'fiow -of fluid tosaid discharge passage, Ia pressure relief and unloading means including an element movable in response to attainment of -a predetermined pressure in said discharge passage, biasing means urging said movable element in a predetermined direction, and a movable part responsive to variations in |an implement induced draft forced applied thereto, the combination of a linkage operatively connecting said valve, unloading means andy movable part comprising a first lever having one end portion thereof pivotally -connected with sai-d movable element of said unloading means for movement therewith and disposed for operative engagement with said valve, said movable element actuating said first lever in response to-attainment of said predetermined pressure to thereby move said valve to a position wherein less fluid is being delivered to said discharge passage, a manual control lever, a link connecting said manual control lever with said first lever at an intermediate portion thereof Iand affording a fulcrum for said first lever, a second lever mounted for swinging movement and having a portion thereof operably connected with the other end portion of said rst lever affording relative swinging movement of said first lever and rendering same actuable by said second lever, and means operably connecting said secon-d lever with said m-ovable part.

5. In an automoatic draft control for a ground working implement operated through means including a pump, Ia discharge passage for said pump, a hydraulic motor connected with said implement and receiving fini-d from said passage, a valve for controlling the flow of fluid to said discharge passage, a pressure relief and unloading means including an element movable in respense to attainment of .a predetermined pressure in said discharge passage, biasing means urging said movable element in a predetermined direction, and a movable part responsive to variations in an implement induced draft force applied thereto, the combination of a linkage operatively connecting said valve, unloading means and movable part comprising, a first lever having one end portion thereof pivotally connected with said movable element of said unloading means for movement therewith and disposed for operative engagement with said Valve, said movable element actuating said first lever in response to attainment of said ypredetermined pressure to thereby move said valve to a position wherein less fluid is being delivered to sai-d discharge passage, a manual control lever, fa link connecting said manual control lever with said first lever at an intermediate portion thereof and affording a fulcrumV for said first lever, a second lever mounted for swinging movement and having .a portion thereof operably connected with the other end portion of said first lever afford-ing relative swinging movement of said rst lever and rendering same actuable by said second lever, and a swingable arm having its free end portion disposed for sliding engagement with an edge of said second lever, said arm being operably connected with said movable part.

6. In a control apparatus having a pump, a valve controlling the flow of fluid from said pump, and a movable part responsive to variations in a f-orce applied thereto, the combination of -a linkage operatively connecting said valve and movable part comprising, .a first lever movably supported with one end portion thereof disposed for operative engagement with said valve, a first arm pivotally connected to an intermediate portion of said first lever and affording a fulcrum for the latter, biasing means urging said first lever to swing in a predetermined direction about said fulc-rurn, a second lever mounted for swinging movement and having a portion thereof operably connected with the other end portion of said first lever affording relative swinging movement of said first lever and rendering same actuable by said second lever, a swingable arm coacting with said movable part and second lever to afford a relatively movable moti-on transmitting connection therebetween, and means positionable to render said swingable arm ineffective to transmit motion between said movable part and said second lever thereby affording relative independent movement of said first lever and movable part. 7. In a control apparatus having a pump, a

vvalve controlling the flow of uid from said pump,

operative engagement with said valve, a manual control lever, a link connecting said manual control lever, a link connecting said manual control lever with said first lever at an intermediate portion thereof and affording a fulcrum for said iirst lever, a second lever mounted for swinging movement and having a portion thereof operably connected with the other end portion of said first lever affording relatively swinging movement of said first lever and rendering same actuable by said secon-d lever, yand means operatively interconnecting said movable part `and said second lever to alf-ord a relatively movable motion transmitting connection therebetween, said means including an element selectively flexible in a position rendering said means incapable of transmitting motion from said movable part to said second lever.

`8. In a control apparatus having a pump, a valve controlling the ow of fluid from said pump, and a movable part responsive to variations Iin a force applied thereto, the combination of a linkage operatively connecting said valve and movable part comprising, a first lever m-ovably supported with one end portion thereof disposed for operative engagement with said valve, a first arm pivotally connected to an -intermediate portion of said first lever and affording a fulcrum for the latte-r, biasing means urging said first lever to swing in a predetermined direction about said fulcrum, a second lever mounted for swinging movement and having a portion thereof operably connected with the other end portion of said first lever aording relative swinging movement of said rst lever and rendering same .actuable by said second lever, said second lever including a curved edge portion, a swingable arm including a portion positioned for sliding engagement with said curved edge portion of said second lever, said swingable arm coacting with said movable part to transmit motion thereof to said second lever, and means positionable to render said swingable arm ineffective to transmit motion between said movable part and said second lever thereby affording relative independent movement of said rst lever and movable part.

9. In a control apparatus having a pump, a valve controlling the ow of fluid from said pump, and a movable part responsive to variations in a force applied thereto, the combination of a link- Iage operatively connecting said valve and movable part comprising, a first lever movably supported with one end portion thereof disposed for operative engagement with said valve, a manually controllable lever mounted for swinging movement about a first axis, a link connecting said manually controllable lever with said first lever at an intermediate portion thereof and affording a fulcrum for said first lever, a second lever mounted for swinging movement about a second axis spaced from and generally parallel to said rst axis, said second lever having a portion thereof operably connected with the other end portion of said first lever affording relative swinging movement of said rst lever and rendering same actuable by said second lever, and a swing- 1S able arm mounted for movement about a third axis spaced from and generally parallel to said first and second axes, said swingable arm having a portion thereof slidably engaging an edge portion of said second lever and being operatively connected with said movable part.

10. In an Iautomatic draf-t control for a ground working implement operated through means including a pump, a discharge passage for said pump, a. hydraulic motor connected with said iinplement and receiving fluid from said passage, a valve for controlling the flowvof fluid to said ldischarge passage, a pressure relief and unloading means including an element movable in response to attainment of -a predetermined pressure in said discharge passage, biasing means urging said movable element in a predetermined direction, and a movable part responsive to variations in an impl-ement induced draft force applied thereto, the combination of a linkage operatively connecting said valve, unloading means and movable part comprising, la rst lever having one end portion thereof pivotally connected with said movable element of said unload-ing means for movement therewith and disposed fo-r operative engagement with said valve, said -movable 'element :actuating said first lever in response to` attainment of said predetermined pressure to thereby move said valve to a position wherein less fluid is being delivered to said discharge passage, a manually controllable lever mounted for swinging movement about a first axis, a link connecting said manually controllable lever with said rst lever lat an intermedi-ate portion thereof and affording -a fulcrum for said first lever, a second lever mounted for swinging movement about a second axis spaced from and generally parallel t0 said first axis, said second lever having ra portion thereof operably connected with the other end portion of said first lever alf-Ording relative swinging movement of said first lever and rendering same actuable by said second lever, :a swingable arm mounted for movement about a third axis spaced from and generally parallel to said first and second axes, said swingable arm having a portion thereof slidably engaging an edge portion of said sec-ond lever, and means operatively interconnecting said movable part and said swingable arm comprising parts coacting to transmit movement of said movable part to said swingable arm and coacting to afford movement of said first and second levers in response to action of said unloading means.

WALTER F. STRE'HLOW.

IGOR KAMLUKIN.

REFERENCES CITED The following references are of record in the lfile Of this patent:

UNITED STATES PATENTS Number Name Date 1,402,648l Pfanhauser Jan. 3, 1922 2,118,181 Ferguson May 24, 1938 2,356,231 Ferguson Aug. 22, 1944 2,405,980 Sands et al Aug. 20, 1946 

